Dentist&#39;s casting appliance.



N. E. SMITH. DENTISTS CASTING APPLIANCE! v APPLICATION FILED FEB-20. 1908. 932,508

Patented Aug. 31, 1909.

Wi tn eases citizen of the United States,

showing an oblong flask.

UNITED' STATES PATENT our-re.

NATHAN H. SMITH, OF SEATTLE, WASHINGTON.

DENTISTS CASTING APPQIANGE.

To all whom it may concern:

H. SMITH, residing at Seattle, in the county of King and State of \Vashington, have inventedcertain new and useful Improvements in Dentists Casting Appliances, of which the following is a specification.

The present invention provides an appli- Be it known that I, NATHAN ance which admits of a form being positivelyand accurately reproduced in metal, henceof especial advantage in casting gold inlays or gold dummies for bridge work or other forms met with in dental work.

' The appliance consists of a suction chamber, means for creating a vacuum thereinand a flask adapted to be fitted to the suction chamber and containing the mold of the form to be reproduced in metal.

For a full understanding of the invention and the merits thereof and also to acquire a knowledge of the details of construction and the means for effecting the result, reference is to be had to the following description and accompanying drawings.

While the invention may be. adapted to conditions by changes in difl'erent forms and the structure and minor-details without departing from the spirlt or essential features thereof, still the preferred embodiment isshown in the accompanying drawings, in which: p Figure 1 is a perspective 'view of an appliance embodying the invention. Fig. 2 is a vertical central section of the suction chamber having a smaller flask and a re ducer'. Fig. 3 1s a detail erspective view ig. 4 is a sectional. View showing the operation 'ofthe invention.

Corresponding and like parts are referred to in the followin description and indicated in all the views 0 the drawings by the same reference characters.

The suction chamber 1 is provided with a base 2 apertured to receive fastenings for securing the suction chamber to a bench,

table or like support. The upper portion of the suction chamber is slightly flared to ading fitted thereto according to the work or form to. bereproduced in metal. A tube 3 connects with a side of the suction chamber and opens therein and has connection at its outer end with a pump ,4 or analogous appliance for producing a vacuum or suction suction chamber, whereas the flask shown in .Fig. 2 is of smaller size and necessitates the provision of'a reducer 6, which latter is of conical form and fits the suction chamber in a mannerto provide an air tight joint, the

flask fitting within the reducer in a similar manner.

In the-construction shown in 3, the

flask 7 is 'J- of oblong form and upwardly flared being designed most especially forbridgework. "The lower end of the flask is provided with a collar 8 which ,snuglv fits the'reducer 6.

.- In the practical operation of this invene within the chamber 1. The pump 4,,il'lus-.

tion, the form to be reproduced in gold or other metal is .invested in a composition formed of two-thirds finely powdered silex and one fthill plaster of paris, mixed in Water. The form or pattern is obtained in .wax. This wax is especially prepared for this purpose and burns out of theinvestment entirely when heated. The investment of the form or model to produce the mold is effected in one of the flasks selected according to the shape and size of the wax mold and isaccomplished by pushing the wax pattern down onto the investment while it 1ssoft. A small wire is connected to the wax pattern and extends upward'through the investment. After the wax pattern has been invested, the case is set'aside to allow the investment to harden. ,A depression is then made in the investment around the sprue wire. The case is then heated and the sprue wire is removed, thus leaving a hole in the investmentmaterial connecting at its inner end with the moldcavity-and at its upper end with the depression in the upper side of the investment material. The mold being form'ed'in the manner stated is set aside to harden, and dry, after which it is heated to burnout the wax form. so cavity for the reception of the moltenmetal. After the investment has been dried'up and heated'it becomes porous enough to allow enough air to pass through it to suck the molten metal into its position inthe mold cavity.

as to produce the While the 'fiask is still hot, it is placed. into the machine and the metal to be used is placed in the depression over the sprue hole and melted (usually with the blow pipe). After the metal has been heated to a molten condition, a vacuum is created in the suction chamber by means of the pump or like device, thereby exhausting the air from the mold cavity and causing the metal to be forced therein by atmospheric pressure so as to fill every part of the mold and insure an accurate reproduction of the required form.

After the casting has been effected the flask is allowed to cool and the investment is easily taken out and broken to admit of the casting being obtained. The same can be finished in any well known manner.

Having thus described the invention, what is claimed as new is: 4

The herein described dental appliance, consisting of a chamber having a base apertured to receive fastenings and having its upper portion flared and provided at a side with a tube to which a suction device is fitted, a tapered flask, and a tapered reducer fitted to the lower end pf said flask and adapted to fit within the flared end of said chamber.

In testimony whereof I afiix my signature in presence of two witnesses.

I NATHAN H. SMITH. [1,. 5,] Witnesses FRANK S. SMITH, FREDERICK W. KELLY. 

